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<html>
<head>
<meta charset="utf-8"> 
<title>菜鸟教程(runoob.com)</title> <!--演示了如何使用百分比值设置元素的高度-->
<style>
    html {height: 100%;}
    body {height: 100%;}
    img.normal {height: auto;}
    img.big {height: 50%;}
    img.small {height: 10%;}
</style>
</head>

<body>
    <img class="normal" src="logocss.gif" width="95" height="84" /><br>
    <img class="big" src="logocss.gif" width="95" height="84" /><br>
    <img class="small" src="logocss.gif" width="95" height="84" />
</body>
</html>